Quick Start
-----------

on Linux:
 $ export JAVA_HOME=/usr/local/java # or wherever you have the JDK installed
 $ make
 $ build/linux-i386-compile-fast/avian -cp build/test Hello

on Mac OS X:
 $ export JAVA_HOME=/Library/Java/Home
 $ make
 $ build/darwin-i386-compile-fast/avian -cp build/test Hello
 
on Windows:

Install the current MSYS from the MinGW page (selecting the C and C++
compilers).  Follow the post-install options to create the file system
link to the compiler.  Upgrade to GNU make 3.81 by downloading the
current release of GNU make from the same download page as the MSYS
download page.  Extract the tarball into your MSYS installation
directory.  Open the MSYS shell and:

 $ export JAVA_HOME="C:/Program Files/Java/jdk1.6.0_07"
 $ make
 $ build/windows-i386-compile-fast/avian -cp build/test Hello

Adjust JAVA_HOME according to your system, but be sure to use forward
slashes in the path.


Introduction
------------

Avian is a lightweight virtual machine and class library designed to
provide a useful subset of Java's features, suitable for building
self-contained applications.  More information is available at the
project web site:

  http://oss.readytalk.com/avian

If you have any trouble building, running, or embedding Avian, please
post a message to our discussion group:

  http://groups.google.com/group/avian

That's also the place for any other questions, comments, or
suggestions you might have.


Supported Platforms
-------------------

Avian can currently target the following platforms:

  Linux (i386 and x86_64)
  Win32 (i386)
  Mac OS X (i386)


Building
--------

Build requirements include:

  * GNU make 3.80 or later
  * GCC 3.4 or later
  * JDK 1.5 or later
  * GNU binutils 2.17 or later (not needed on OS X)
  * MinGW 3.4 or later (only if cross-compiling for Windows)
  * zlib 1.2.3 or later

Earlier versions of some of these packages may also work but have not
been tested.

If you are cross-compiling for Windows, you may find it useful to use
our win32 repository: (run this from the directory containing the
avian directory)

  $ git clone git://oss.readytalk.com/win32.git

This gives you the Windows JNI headers, zlib headers and library, and
a few other useful libraries like OpenSSL and libjpeg.

The build is directed by a single makefile and may be influenced via
certain flags described below.

 $ make platform={linux,windows,darwin} arch={i386,x86_64} \
     process={compile,interpret} mode={debug,debug-fast,fast,small}

  * platform - the target platform
      default: output of $(uname -s | tr [:upper:] [:lower:])

  * arch - the target architecture
      default: output of $(uname -m)

  * mode - which set of compilation flags to use, which determine
    optimization level, debug symbols, and whether to enable
    assertions
      default: fast

  * process - choice between pure interpreter or JIT compiler
      default: compile


Installing
----------

 $ cp build/${platform}-${arch}-${process}-${mode}/avian ~/bin/


Embedding
---------

The following series of commands illustrates how to produce a
stand-alone executable out of a Java application using Avian.

Step 1: Build Avian, create a new directory, and populate it with the
VM object files and bootstrap classpath jar.

 $ make
 $ mkdir hello
 $ cd hello
 $ ar x ../build/${platform}-${arch}-${process}-${mode}/libavian.a
 $ cp ../build/classpath.jar boot.jar

Step 2: Build the Java code and add it to the jar.

 $ cat >Hello.java <<EOF
public class Hello {
  public static void main(String[] args) {
    System.out.println("hello, world!");
  }
}
EOF
 $ javac -bootclasspath boot.jar Hello.java
 $ jar u0f boot.jar Hello.class


Step 3: Make an object file out of the jar.

for linux-i386:

 $ objcopy -I binary boot.jar -O elf32-i386 -B i386 boot-jar.o

for linux-x86_64:

 $ objcopy -I binary boot.jar -O elf64-x86-64 -B i386:x86-64 boot-jar.o

for windows-i386:

 $ objcopy -I binary boot.jar -O pe-i386 -B i386 boot-jar.o

for darwin-i386: (objcopy is not currently supported on this platform,
so we use the binaryToMacho utility instead)

 $ ../build/darwin-i386-compile-fast/binaryToMacho boot.jar \
     __binary_boot_jar_start __binary_boot_jar_end > boot-jar.o


Step 4: Write a driver which starts the VM and runs the desired main
method.  Note the bootJar function, which will be called by the VM to
get a handle to the embedded jar.  We tell the VM about this jar by
setting the classpath to "[bootJar]".

 $ cat >main.cpp <<EOF
#include "stdint.h"
#include "jni.h"

#ifdef __MINGW32__
#  define EXPORT __declspec(dllexport)
#  define SYMBOL(x) binary_boot_jar_##x
#else
#  define EXPORT __attribute__ ((visibility("default")))
#  define SYMBOL(x) _binary_boot_jar_##x
#endif

extern "C" {

  extern const uint8_t SYMBOL(start)[];
  extern const uint8_t SYMBOL(end)[];

  EXPORT const uint8_t*
  bootJar(unsigned* size)
  {
    *size = SYMBOL(end) - SYMBOL(start);
    return SYMBOL(start);
  }

} // extern "C"

int
main(int ac, const char** av)
{
  JavaVMInitArgs vmArgs;
  vmArgs.version = JNI_VERSION_1_2;
  vmArgs.nOptions = 1;
  vmArgs.ignoreUnrecognized = JNI_TRUE;

  JavaVMOption options[vmArgs.nOptions];
  vmArgs.options = options;

  options[0].optionString = const_cast<char*>("-Djava.class.path=[bootJar]");

  JavaVM* vm;
  void* env;
  JNI_CreateJavaVM(&vm, &env, &vmArgs);
  JNIEnv* e = static_cast<JNIEnv*>(env);

  jclass c = e->FindClass("Hello");
  if (not e->ExceptionOccurred()) {
    jmethodID m = e->GetStaticMethodID(c, "main", "([Ljava/lang/String;)V");
    if (not e->ExceptionOccurred()) {
      jclass stringClass = e->FindClass("java/lang/String");
      if (not e->ExceptionOccurred()) {
        jobjectArray a = e->NewObjectArray(ac-1, stringClass, 0);
        if (not e->ExceptionOccurred()) {
          for (int i = 1; i < ac; ++i) {
            e->SetObjectArrayElement(a, i-1, e->NewStringUTF(av[i]));
          }
          
          e->CallStaticVoidMethod(c, m, a);
        }
      }
    }
  }

  int exitCode = 0;
  if (e->ExceptionOccurred()) {
    exitCode = -1;
    e->ExceptionDescribe();
  }

  vm->DestroyJavaVM();

  return exitCode;
}
EOF
 $ g++ -I$JAVA_HOME/include -D_JNI_IMPLEMENTATION_ -c main.cpp -o main.o


Step 5: Link the objects produced above to produce the final
executable, and optionally strip its symbols.

on Linux:
 $ g++ -rdynamic *.o -ldl -lpthread -lz -o hello
 $ strip --strip-all hello

on Mac OS X:
 $ g++ -rdynamic *.o -ldl -lpthread -lz -o hello -framework CoreFoundation
 $ strip -S -x hello

on Windows:
 $ dlltool -z hello.def *.o
 $ dlltool -k -d hello.def -e hello.exp
 $ g++ hello.exp *.o -L../../win32/lib -lmingwthrd -lm -lz -lws2_32 \
     -mwindows -mconsole -o hello 
 $ strip --strip-all hello.exe